1. Field of the Invention
The present invention generally relates to a position determination system that utilizes visible light communication. More particularly, the invention relates to a position determination system that determines the position of a moving object such as a vehicle.
2. Description of the Related Art
In recent years, position determination systems utilizing the global positioning system (GPS) have been widely used as system for determining the present position of a vehicle, a representative example of which is an automobile. Each position determination system of this type is incorporated in, for example, a car-navigation apparatus.
Recently, position determination systems that utilize a visible-light communication system have been proposed as high-precision position determination systems. The visible-light communication system uses visible optical signals and can transmit visible optical signals modulated with position data that is necessary for the position determination function. (See, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-81703.)
Visible optical signals used in such a position determination system may be used in combination with stereoscopic video data generated by a plurality of video cameras mounted on a vehicle. This makes it possible to determine the present position of, for example, an automobile running on a road.
Any system that uses a plurality of cameras mounted on each vehicle, however, is expensive due to not only the use of cameras, but also the use of an apparatus that performs complex signal processing, such as the processing of stereoscopic video signals. In view of this, the position determination system of this type can hardly be put to practical use.